Improved Radio Acoustic Sounding Techniques

Abstract

Improved radio acoustic sounding system (RASS) technology for use with radar wind profilers has been developed and applied to 915-MHz and 50-MHz profilers. The most important advance is the simultaneous measurement of the wind velocity to correct the acoustic velocity measurement for air motion. This eliminates the primary source of error in previous RASS measurements, especially on short time scales. Another improvement is the use of an acoustic source that is controlled by the same computer that controls the radar. The source can be programmed to produce either a swept frequency or a random hopped frequency signal. Optimum choices of the acoustic source parameters are explored for particular applications. Simultaneous measurement of acoustic and wind velocity enables the calculation of heat flux by eddy correlation. Preliminary heat flux measurements are presented and discussed. Results of the use of RASS with oblique beams are also reported.